The present invention relates to a new and improved construction of a steamer for treatment of a continuously through-passing textile web which, throughout a certain residence time, is exposed to the action of suitable reaction means.
In order to be able to particularly treat cotton fabrics and cotton-wool mixed fabrics so as to achieve a faultless dye absorbtion or to ensure that the pretreatment prior to fabric printing is faultless, it is already known to the art to use a so-called continuous installation wherein a textile web which is to be processed is delivered continuously in a spread apart condition through a steamer and is heated therein during a predetermined residence time and exposed to the action of certain predetermined chemicals. On the one hand, this treatment is intended to promote the removal of husks and, on the other hand, to obtain the desired absorbancy, levelness and whiteness.
The effectiveness of this treatment is dependent upon two factors, namely upon the residence time of the web material which is being treated within the steamer and upon the quantitative amounts of chemicals employed during treatment.
Two different concepts of steamer have been developed by the textile processing industry.
According to a first concept it is intended that the consumption of chemicals be reduced to a minimum in that the residence time of the web within the steamer is as great as possible. In order to maintain the dimensions of such steamer within tolerable limits it has been proposed, for instance as disclosed in the German Patent Publication No. 2,605,292, to guide the continuously infed and outfed web within the confines of the steamer, initially in a wide condition, over deflection rolls and thereafter to convey such web, while plaited in folds, upon a sieve or filter band arranged below the deflection roll-guide arrangement. Upon this sieve band the web is further transported in a piled state in an orderly array of loop layers, so that with small spatial requirements there can be obtained an appreciable increase in the residence time.
However, with certain qualities of the web material the transport of the web through the pretreatment steamer in the form of a tightly pressed together fabric stack or pile causes the formation of crease folds and fold marks.
According to another concept which has been developed, particularly suitable for pronouncedly fold sensitive web qualities, the web is guided in a spread apart or open-width condition throughout its entire path of travel through the steamer, and rows of deflection rolls are arranged such that the web is guided throughout as long as possible travel path within the steamer. Nonetheless within such steamer, if its dimensions are held within tolerable limits, there only can be obtained a residence time which is less by a multiple in comparison to that which is realizable within a steamer of the previously mentioned type, which, in turn, again only can be counteracted by a more intensive employment of the treatment chemicals.
Hence, both systems have certain advantages for predetermined web or cloth qualities, and it is for this reason that processing plants frequently have steamers of both constructional types or designs. Yet, apart from the equipment expenditure associated therewith and the space requirements needed, further drawbacks worthy of mention in this respect are that when changing from one steamer to another steamer each time the web must be newly threaded through the steamer and the subsequent devices of the treatment installation. Also, appreciable energy losses result due to cooling of the installation during the downtimes.